Hollow fiber membrane module

ABSTRACT

The present invention relates to hollow fiber membrane modules for use as “immersion modules” in filtration and/or dialysis methods, in particular whenever impairments due to fouling effects are expected from the use of liquids that are contaminated or lead to deposits. The hollow fiber membrane module comprises at least one housing and a plurality of tubular hollow fiber membranes which are arranged parallel to one another in and/or around the housing in a packing space, wherein the volumetric ratio of all the hollow fiber membranes arranged in the packing space to the packing space is less than 20%. Methods for producing such hollow fiber membrane modules are also provided.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to hollow fiber membrane modulesfor use as what are termed “immersion modules” in filtration and/ordialysis methods, in particular whenever impairments due to foulingeffects are expected on the basis of the use of liquids that arecontaminated or lead to deposits, as well as to methods for producingsuch hollow fiber membrane modules.

[0002] Synthetic membranes have been used for separating materials forsome years in industry, for example in sewage treatment or inbiotechnology. In this case, a role is played, in particular, by theprocessing of aqueous systems, but also by the separation of gases ormixtures of organic liquids. In addition to membranes made principallyfrom organic materials, for example polysulfones, there are alsomembranes that consist of inorganic materials such as, for example,aluminum oxide, carbon fibers and zirconium oxide, and which canwithstand temperatures of up to 400° C.

[0003] By using pressure or underpressure, membrane filtration methodscan be applied both continuously and discontinuously as ultrafiltrationor, together with a concentration difference, as diafiltration. In thecase of filtration volumes <1000 ml, filter cells are frequentlyequipped with membrane flat filters, whereas capillary or hollow fibersystems are used for larger volumes. The term capillary or tube membraneis used where the diameter of the tubular membrane >1 mm, and the termhollow fiber membrane when the diameter <1 mm, the diameter of adialysis membrane typically being 0.2 to 0.5 mm.

[0004] Membranes for filtration or dialysis methods constitute thinfilm-like, either “dense” or porous separating layers. Depending on poresize, the porous separating layers are permeable only for specificmolecule or particle sizes whereas, depending on the solubility anddiffusivity of the materials to be separated in the substance of theseparating layers, “dense” separating layers permit the materials topermeate faster or slower and therefore lead to separation. Membranesfrequently have a foam-like support structure, with 60% to 80% hollowspace, which supports the actual separating layer. Asymmetricallyconstructed membranes consist of a highly porous support structure inthe case of which the size of the cavities inside the support structuredecreases toward the side which supports the actual separating layer.

[0005] In order to process relatively large volumes of solution,tube-shaped membrane bundles made from hollow fibers or capillarymembranes which permit a larger passage of solutions because of a largemembrane surface, are introduced directly into the solution to beprocessed as what are termed immersion modules. In order to protect themembrane bundles against mechanical damage, which could be effected, forexample, by forces arising from the liquid flow, the membrane bundlesare frequently accommodated in a housing that lends the hollow fibermembranes sufficient protection and stability toward the outside. Inthis case, the housing has openings that are intended to permit theexchange of solutions between the housing interior, that is to say thehollow fiber membranes, and the medium in which the hollow fibermembrane module has been immersed.

[0006] In the design normally employed for a membrane module and whichcannot be designated as an immersion module, the walls of the protectinghousing have no openings, that is to say they are impermeable, andinstead of this the housing has two connections, specifically a feedline and a withdrawal line through which the medium to be processed isfed to the outer surfaces of the hollow fibers and then led away againfrom the latter.

[0007] In the case of such normally used modules, the aim is as high apacking density as possible, which means that as many hollow fibermembranes as possible are accommodated in parallel in the housinginterior, and the housing therefore has a high packing density. The term“packing density” refers in percentage terms to the ratio of the volumeof all the hollow fiber membranes including their wall volume to thevolume of the housing in which the hollow fibers are arranged. A highpacking density therefore means a low volume for the hollow or freespaces inside the housing that are formed between the tubular membranefibers. A natural upper limit to the packing density of <100% resultsfrom the fact that it is possible to arrange in parallel inside thedefined volume of the housing only a number of tubular membranes whichis such that they do not exhaust the prescribed volume. The limitationarises because when the tubular membranes touch interspaces are producedthat are not tubular in shape and therefore leave over a residual cavityeven given the most ideal arrangement. The packing density is, however,limited in addition by two further important factors. On the one hand,when potting the hollow fiber ends it is necessary to introduce sealingmaterial between the hollow fibers and, on the other hand, the solutionsbeing used are also to flow around the hollow fibers at the outersurface, so that, depending on the mode of operation of the module, itis possible either to bring a solution to be filtered into contact withthe membranes, or, instead, to lead off filtrate. The hollow fiberbundles must be embedded at their ends in what is termed pottingmaterial so as to produce at each end in this way, just as in the caseof shell-in-tube heat exchangers, a tube sheet denoted below as a“potting”. The result of this is the production, together with thehousing into which the bundle is introduced, of two spaces that areseparated by the membrane. The separated spaces thus produced can thenrespectively be provided with a feed line and a withdrawal line, inorder to supply the feed to be treated to one space and to lead ittherefrom as retentate, and to lead off the filtrate obtained from thefeed from the other space.

[0008] The packing density of the normally used, conventional hollowfiber membrane modules is therefore approximately 25% to 30%.

[0009] Conventional hollow fiber membrane modules are designed chieflyfor use in particle-free solutions, that is to say solutions or mediathat are not contaminated or do not tend to deposits. Such conventional,densely packed membrane modules with a perforated module housing are,however, frequently likewise used for technical processes in whichparticle-containing media, for example contaminated liquids in sewagetreatment. Particularly in the case of such particle-containing media,what is termed fouling occurs in the course of the filtration process,that is to say in the course of time deposits that diminish ever morestrongly the permeability of the membranes for the materials to beseparated are increasingly formed on the membrane surfaces. This can goso far that the convective transport inside the hollow fiber membranemodule, that is to say between the hollow filaments, is stoppedcompletely, and that the transport performance of the entire moduledrops by orders of magnitude, since only a low percentage of the overallmembrane surface area accommodated in the module still remains availablefor separating materials. If, for example, bundles of hollow fibers areused, it is possible, in particular, only for the hollow fibers arrangedon the outer circumference of the bundle to participate in theconvective transport of the exterior. In the case where the hollowfibers are arranged in the interior of the module, during the mostexceptional case, it is only diffusion processes that still occur, butthey are likewise greatly impaired because of the deposits.

[0010] It is normal to apply chemical or mechanical cleaning methodssuch as backflushing, mechanical vibration, ultrasound methods etc. inorder to remove deposits from fouling processes. Apart from the factthat these cleaning methods are associated with a high outlay on energy,they always harbor the risk of mechanical damage to the hollow fibermembranes. If these customary measures can no longer be applied, theonly measure remaining is a suitable incident flow onto the membranesurface through the feed solution.

[0011] In order to suppress fouling processes specifically in the caseof applications in the revival pools of sewage-treatment plants, afiltration method (WO 99/29401; Zenon Environmental, Inc., Burlington,Ontario, Calif.) has been developed in which capillary membranes areintroduced into the aeration tanks directly without a protectivehousing. In order to keep the fibers free from deposits, they are bathedwith a uniform stream of air bubbles. However, these fibers have apartially substantially larger diameter than the fibers normally used,which have a diameter of less than 1 mm. They also have thick supportstructures. Moreover, these hollow fibers can be used only at suchpoints in the aeration tank at which the mechanical forces induced bythe flow are very small or can be kept very small. In this specificapplication, the spaces between the individual capillary membranes areup to several millimeters.

[0012] Also known in the art are commercially available hollow fibersystems in which several individual, tightly packed modules areaccommodated in a housing, for example, with a packing density of 20 to35%, in parallel interconnection. The result of this in principle isisolated strands between which there is sufficient space to ensurebetter incident flow or throughflow of the individual strands, and tominimize fouling processes. However, such systems require a technicallyvery complicated housing whose production is correspondingly expensive.

[0013] In addition, use of what are termed spacers is known in the caseof wound modules surrounding flat membranes, or electrodialysis stacks.The spacers are intended, for example, to ensure uniform spacingsbetween the individual membranes and, on the other hand, simultaneouslyto distribute the flow of the solution into the respective feed-side orpermeate-side compartments of the membrane module, in order thus toeffect a flow over the entire membrane. The spacer materials used arereticulate structures with mesh sizes of different magnitude. However,these conventional spacer materials lead to an additional pressure dropin the liquid flow which can be equalized only by an additionalexpenditure of energy. Conventional modules

[0014] with spacers therefore require a forced flow through theirexterior.

SUMMARY OF THE INVENTION

[0015] The present invention provides a hollow fiber membrane module forfiltration, diafiltration and/or dialysis methods, comprising at leastone housing and a plurality of tubular hollow fiber membranes which arearranged parallel to one another in and/or around the housing in apacking space, wherein the volumetric ratio of all the hollow fibermembranes arranged in the packing space to the packing space is lessthan 20%.

[0016] The present invention also provides a method for producing ahollow fiber membrane module, comprising rolling a shaped piece togetherto produce a housing shape, and arranging the hollow fiber membranes inand/or around the housing in a packing density of less than 20%.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 shows a schematic of an intermediate step in the productionof the hollow fiber membrane module according to the invention,

[0018]FIG. 2 shows an embodiment of the hollow fiber membrane moduleaccording to the invention in a perspective view and in cross section,as well as another embodiment in cross section,

[0019]FIG. 3 shows a further embodiment of a hollow fiber membranemodule according to the invention in a perspective view with variousexemplary embodiments of segmentation elements,

[0020]FIG. 4 shows the embodiment of the hollow fiber membrane moduleaccording to the invention from FIG. 3, filled with hollow fiberbundles, in perspective view,

[0021]FIG. 5 shows a further exemplary embodiment of the hollow fibermembrane module according to the invention which was produced fromstainless steel wire, in its development and in cross section, and

[0022]FIG. 6 shows a further exemplary embodiment of the hollow fibermembrane module according to the invention, building on the exemplaryembodiment in FIG. 2 with segmentation elements that are shorter thanthe module length, in a perspective view.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides a hollow fiber membrane modulethat is suitable for use as an immersion module in the most diversemembrane material separation methods, and in the case of which theformation of deposits on the membrane surfaces, which is caused by theinadequate incident flow onto the membranes, is removed as far aspossible or completely during the separation method, in the case ofwhich module there is an effective flow around, or incident flow onto,the hollow fiber membranes arranged to form bundles, and in the case ofwhich module the material transport from the feed space into thepermeate space remains virtually constant during the entire materialseparation process, it also being possible to use the hollow fibermembrane module both in particle-free media or solutions and inparticle-containing media or solutions, in particular contaminated mediaor media tending to deposits.

[0024] The hollow fiber membrane modules according to the inventioninfluence the flow conditions in the space between the hollow fibers,that is to say in the outer space of the hollow fibers, but not the flowin the lumen of the hollow fibers.

[0025] The present invention provides a hollow fiber membrane modulethat is designed, in particular, for use as an immersion module forbiotechnical processes and has the following features:

[0026] The hollow fiber module comprises at least one preferablycylindrical housing that is preferably provided with openings in thelateral surface, and a plurality of hollow fiber membranes that areaccommodated in or on the housing in a packing space and have anidentical or different cross section, which are arranged parallel to oneanother, in particular with the formation of free spaces, the ratio ofthe volume of all the hollow fiber membranes arranged in the packingspace, including their walls, to the volume of the packing space beingless than 20%.

[0027] In connection with the present invention, the term packing spaceis understood as the housing interior enveloped by the housing of themodule, to the extent that hollow fiber membranes are arranged in saidinterior. If hollow fiber membranes are arranged outside the housing,the term packing space is understood as the space located outside thehousing in which the hollow fiber membranes are arranged, and which isformed inward by the outer surface of the housing and outward by aninner lateral surface enveloping the space containing the membranehollow fibers, of a second housing, situated radially outward, or by acorresponding imaginary envelope or lateral surface. In a preferreddesign, this envelope makes contact with the peripheral edges ofsegmentation elements that are present in this embodiment. This lateralsurface or envelope is the inner surface of a channel that is annularwhen seen in cross section. In particular, the channel has a circularcross section. In a preferred design, the inwardly situated housing hasa circular cross section, the annular channel, surrounding this housing,of the outer housing, or the imaginary lateral surface being arrangedconcentrically with the housing. If membrane hollow fibers are arrangedboth inside and outside the inner housing, the packing space constitutesthe space both inside and outside the inner housing, and thus the spacethat is embraced by the outer envelope of the overall space of themodule, that is to say the inner surface of the annular channel.

[0028] In connection with the present invention, the term packingdensity is understood as the ratio of the volume of all the hollow fibermembranes arranged in the packing space, including the volume of theirwalls, to the volume of the packing space, expressed in percentageterms.

[0029] Thus, it is provided according to the invention that the packingdensity of the hollow fiber membrane module according to the inventionis low and less than, preferably much less than 20%.

[0030] In a preferred embodiment, the packing density can also bedescribed by the ratio of the sum of the cross sections of all thehollow fibers in the packing space to the cross section of the packingspace. The packing density of the hollow fiber membrane module accordingto the invention is therefore substantially smaller than the hollowfiber membrane modules known in the prior art, whose packing density is25% to 30%. According to the invention, the modules have a largeproportion of free spaces, that is to say of packing space in which nohollow fiber membranes are arranged over the entire length of themodule. Moreover, the lateral surface of the module housing is providedwith very large openings such that an unimpeded exchange of liquid cantake place between the hollow fibers arranged in the housing interiorand the liquid or the medium in which the module is accommodated,without impairing the stability of the lateral surface of the housing.As dictated by the low packing density and the very large surface areaof the openings in the lateral surface, based on the overall surfacearea of the lateral surface of the housing, the flow of the liquid or ofthe medium can pass through the module more effectively and thusactively prevent the formation of deposits on the surfaces of theindividual hollow fibers.

[0031] In connection with the present invention, the term hollow fiberbundle or hollow fiber membrane bundle is understood as hollow fibers orhollow fiber membranes that are respectively arranged in a compartmentdelimited by segmentation elements. In this case, the hollow fibers canbe held together among one another inside the arrangement by connectingstructures, for example by elements running radially around the bundles,or they can also be arranged loosely next to one another, according tothe invention, however, at a spacing that permits effective flow aroundthe fibers. Hollow fiber bundles preferably extend over the entirelength of the module housing.

[0032] In further preferred embodiments of the invention, it is providedthat several spaced apart hollow fiber bundles are arranged in arelatively low packing density in or on the housing provided withopenings, the individual hollow fiber bundles being separated spatiallyfrom one another by segmentation elements fitted on the housing. Thelongitudinal axis of the segmentation elements extends parallel to thelongitudinal axis of the housing and preferably over the entire lengthof the housing.

[0033] In one embodiment, the segmentation elements are fitted on theinner surface of the lateral surface of the housing provided withopenings, and therefore project into the interior of the housing, thusproducing in the interior of the housing compartments that can be filledwith hollow fibers. The hollow fiber bundles are therefore arranged inthe interior of the housing in this refinement.

[0034] In a further refinement of the invention, the segmentationelements are fastened on the outer surface of a first housing cylinderthat, in particular, has openings in the lateral surface. The hollowfiber membrane bundles preferably fixed on the segmentation elements aretherefore arranged on the outside of the lateral surface of the firsthousing cylinder. In this refinement, the entire module for reasons ofstability in a further preferred embodiment of the invention isintroduced into a second cylindrical housing that can be of circulardesign when seen in cross section. The second housing forms, as it were,the envelope of the packing space situated outside the inner housing andcan be configured as a cage, for example. Together with the segmentationelements, the inner and outer cylinders preferably form a segmentedannular channel.

[0035] The segmentation elements according to the invention that areused in these two embodiments differ from the spacer elements describedin the prior art both with regard to their shape and with regard totheir arrangement in or on the housing. The segmentation elementscomprise a frame part that surrounds a large free passage surface. Bycomparison with the modules described in the prior art, the volume ofthe free spaces inside the modules according to the invention issubstantially enlarged once more, and thus the packing density in themodules according to the invention is substantially diminished, owing tothe large passage surface and also to the specific arrangement of theseelements in the module, which entails a specific arrangement of thehollow fiber membrane bundles in or on the housing. The packing densityinside the module according to the invention is below 10%, in particularbelow 5%, referred to the total number of the hollow fibers of all thebundles of a hollow fiber membrane module according to the invention.The specific configuration of the segmentation elements according to theinvention likewise substantially reduces the resistance of the flow ofthe solution or the medium, such that the flow can more effectively flowaround the hollow fibers arranged in the module, and thus the formationof deposits on the surfaces of the individual hollow fibers can beactively prevented.

[0036] The feed solution can flow turbulently over the individual hollowfiber membranes inside the module owing to the low packing density ofthe hollow fiber modules according to the invention inside the module,to the use of segmentation elements according to the invention with verylarge passage surfaces in preferred embodiments, and to the use of amodule housing with very large openings. It is true, on the one hand,that in this way the high membrane surface areas of the hollow fibermodules previously described in the prior art are not achieved, but inaccordance with the invention the transport coefficients vary onlyslightly during the entire separation process such that, by contrastwith conventional hollow fiber membrane modules, the variable that isdecisive for the exchange of materials, specifically the product of themembrane surface area and transport coefficient, remains virtuallyconstant during the entire process. By contrast with conventionalmembrane modules, the material transfer rates in the hollow fiber moduleaccording to the invention are therefore lower at the start of thefiltration process but are substantially higher on average over timethan in the case of conventional devices in which severe fouling occursin the course of time.

[0037] In connection with the present invention, the hollow fibermembrane or tubular hollow fiber membrane is understood as a technicalmembrane, with particular preference as a thin, film-like and porousseparating layer. Such a porous membrane can also have a homogeneoussupporting layer of foam-type design, especially when it is particularlythin. According to the invention, the use of membranes with ahomogeneously designed supporting layer is just as possible as the useof membranes with an asymmetric supporting layer. It is preferred forthe membrane module according to the invention to be a membrane filterwhose membrane can, in a preferred way, be produced, for example, fromceramic or polymeric materials such as, for example, cellulosederivatives, polyamides, polyvinylchloride, polysulfone and/or teflon,and can consist thereof or contain the same in substantial portions, inparticular more than 50% by weight. In the particularly preferred way,the material used to produce the membrane can be sterilized withsuperheated steam. The membranes preferably have a thickness of 50 to250 μm. The membranes used in accordance with the invention arepreferably designed as a tube membrane or tubular membrane.

[0038] In a particularly preferred embodiment, the invention providesthat the tube membrane consists of a polymeric material. Of course, itis also possible to use other tube membranes, for example a ceramic tubemembrane, as long as they have substantially tubular shapes and a porediameter that has an appropriate selection limit, that is to sayseparation limit, in accordance with the respective field ofapplication, such that specific particles, for example bacteria,viruses, cells of human, animal or plant origin, parts thereof and/orhigh-molecular substances are held back, whereas other particles oflower molecular weight can pass through the membrane without hindrance.It is also possible to use filtration hollow fibers, in particularmicrofiltration hollow fibers. The inside diameter of the tubularmembrane is in a range from 0.2 to 2 mm in a particularly preferredembodiment of the present invention.

[0039] The individual hollow fiber membranes can be present inside themodule housing in any desired arrangement as long as the freedom ofmovement of the individual hollow fibers in the flow is limited to theextent that no breaking or tearing of the hollow fibers occurs. Thearrangement is substantially determined by the material properties ofthe material used to produce the hollow fibers, and/or by the specificintended use of the finished module. If the hollow fibers consist, forexample, of a relatively flexible material and the hollow fiber moduleis to be used in media in conjunction with a relatively strong flow, itis advantageous to combine the hollow fibers to form a bundle or strand,and then to integrate them in the housing provided with openings, inorder thus to obtain an additional fixation and/or stabilization of thefibers.

[0040] In connection with the present invention, the term “identical ordifferent cross section” means that the cross sections of individualhollow fiber membranes, that is to say the surfaces of intersection ofthe hollow fibers obtained by a flat cut perpendicular to thelongitudinal axis of tubular hollow fibers, can be identical ordifferent with reference to the shape and with reference to the size.For example, the cross sections can have the shape of a circle, theshape of an ellipse or a transitional shape between circle and ellipse.

[0041] In connection with the invention, the expression “hollow fibersthat are arranged parallel to one another with the formation of freespaces” means that the hollow fibers located inside or/and outside themodule housing are arranged parallel to one another in such a way thatnot only are there obtained the free spaces which are produced in thecase of a packing, theoretically as dense as possible, of prescribedcylindrical bodies in a larger housing of defined volume, that is to sayof the packing space occurring naturally between these bodies, but thatthere is additional free space present in the packing space, for examplebetween the hollow fibers. It is also to be taken into account that, inparticular, hollow fibers made from polymeric materials are not rigid,ideally cylindrical fibers, but flexible structures frequently deviatingin detail sharply from the cylindrical shape. To this extent, a parallelarrangement means the parallel alignment of the respective averagedirection of the hollow fibers.

[0042] It is provided according to the invention that the first and/orsecond housing of the module preferably has the shape of a cylinder orof what is termed a filter tube. The cylindrical housing offersadvantages in many respects. On the one hand, hollow fibers can bearranged in the housing so as to provide optimal conditions for theirfunctioning, specifically the separation of materials from solutions. Onthe other hand, it offers the tubular hollow fibers a particular measureof protection against mechanical damage, in particular against anexcessively high mechanical loading by the liquid flow which couldotherwise break or tear the fibers, which are exceptionally sensitive insome instances. The cross section of the cylindrical housing can havethe shape, for example, of a circle, an ellipse or a regular polygon,for example a hexagon or an octagon.

[0043] So that it is also possible for sufficient liquid to flow fromthe surroundings through the first and/or second housing into thehousing interior, the lateral surface of the housing cylinder ispreferably provided with sufficiently large openings. According to theinvention, it is provided, in particular, that the individual openingshave characteristic dimensions of several millimeters. If, for example,these openings are squares in plane projection, their side length as afunction of the diameter of the housing cylinder is preferably 3 mm to20 mm, in particular 5 mm to 15 mm, preferably 7 mm to 12 mm. The ratioof the total surface area of the openings to the lateral surface of thecylinder is preferably not over 0.7. This ensures that sufficient liquidcan flow through the housing into the interior. On the other hand, theratio of the total surface area of the openings to the lateral surfaceof the cylinder is preferably not below 0.2, thus ensuring adequatemechanical stability of the housing. This is particularly important whenthe plastics normally used to produce the module housing become softowing to a rise in temperature during the separation process. The wallthickness of the housing cylinder is determined by the requiredmechanical strength and can, depending on the material, be between 0.7and 10 mm, preferably between 1 and 4 mm.

[0044] Any desired materials can be used for the first or second modulehousing, provided that these materials can lend the module sufficientstability. With reference to the physical properties, in this case thesematerials can be both flexible and rigid ones such as, for example,stainless steel. Particularly preferred, the material used for producingthe module housing can be sterilized with superheated steam. Accordingto the invention, the use of plastics, especially of polypropylene, isparticularly preferred because, on the one hand, it can be processedeffectively as a thermoplastic, while on the other hand it still hassufficient mechanical stability even at 121° C., the temperaturenormally applied in the case of sterilization with superheated steam.According to the invention, the lateral surface of the module housingcan be produced in one piece. However, it can also consist of aplurality of individual parts that are connected to one another, forexample, via hinges or other connecting elements. If the module housingcomprises several individual parts, these can consist of the samematerial or of different materials. In a preferred embodiment, theindividual parts consist of the same material and also have the samedimensions.

[0045] In an advantageous embodiment of the invention, it is providedthat the hollow fiber membrane module additionally has a first housingconnection that serves for feeding a solution or a medium to the fiberinterior of the hollow fiber membrane bundle, and is preferably fittedat one end of the housing cylinder. In an advantageous refinement, thehollow fiber membrane module is, however, equipped with a second housingconnection, which serves for withdrawing the solution or the medium or afiltered solution from the fiber interior, whose material compositionhas now been changed by the separation process taking place in themodule, and is preferably fitted at the other end of the housingcylinder. In this embodiment, the convective material transport outsidethe fibers is produced by the flow of the surroundings, in which themodule is immersed. It is provided according to the invention that thisembodiment according to the invention of the hollow fiber membranemodule provided with the two housing connections is used, in particular,in a stirred-tank reactor.

[0046] In a particularly preferred embodiment of the invention, it isprovided that a plurality of spaced-apart hollow fiber bundles arearranged in a low packing density in a, preferably cylindrical, housing,the hollow fiber bundles being separated spatially from one another bysegmentation elements fastened on the inner lateral surface of thecylinder. The segmentation elements according to the invention thereforeproject into the interior of the housing cylinder, and lead to acompartmentalization of the housing interior, the hollow fiber bundlesbeing arranged in the compartments thereby produced. The hollow fibermembrane module is lent additional stability by installation of thesegmentation elements.

[0047] The segmentation elements according to the invention form apreferably rectangular frame part that fixes the external dimensions ofthe segmentation elements. The frame part encloses a free passagesurface. In connection with the present invention, the term “passagesurface of the frame part” relates to the material-free surface(s)surrounded by the frame part, which permits unimpeded passage of liquidsin both directions between two adjacent compartments separated from oneanother by the segmentation element. The passage surface can, ifappropriate, be interrupted by stabilization elements arranged insidethe frame part, such as transverse struts or lattice structures, whichserve for stabilizing the frame part and thus the segmentation element.Depending on the envisaged field of use of the hollow fiber module,these stabilization elements can be of different width referred to thedimensions of the frame part or the passage surface, the stabilizationelements being preferred to be relatively narrow. Likewise, the spacingbetween the stabilization elements can differ, relatively large spacingsbeing preferred according to the invention.

[0048] It is provided according to the invention that, referred to thetotal surface of the stabilization elements, that is to say thetransverse struts or the lattice structure, the passage surface embracedby the frame part is below 20%, preferably below 10%, with particularpreference 2%.

[0049] According to the invention, it is provided that the segmentationsections consist of any desired material, as long as this has adequatestability characteristics such that the spacings between the individualhollow fiber membrane bundles can be ensured over lengthy time periods,and the hollow fiber membrane module is lent additional stability. It ispreferred to use for producing the segmentation element materials thatcan be sterilized with superheated steam. The segmentation elements canbe produced from the same materials as the material used to form thecylinder, but can also consist of other materials.

[0050] The dimensions of the individual segmentation elements usedinside a module can be the same or different. In a preferred embodiment,all the segmentation elements have a length that is equal to the lengthof the housing cylinder, and a height that is, for example, equal to theradius of the cross section of the housing cylinder, or smaller thansaid radius. In a further preferred embodiment, the segmentationelements are shorter than the housing and are distributed over thelength of the housing with appropriate axial interspaces, no furthersegmentation element being arranged inside these axial interspaces overthe full azimuth angle inside the housing. In yet a further preferredembodiment, the segmentation elements are as long as the pottingsprovided at the ends of the housing and are arranged at the housing endssuch that these pottings are segmented. In a preferred embodiment, theheight of the segmentation elements is smaller than the radius of thecross section, and the segmentation sections have additional elements,in particular spacers, on the side diverted from the inside of thehousing cylinder. These spacers are, for example, strips fitted on oneor both sides on the longitudinal edge, averted from the housing wall,of the frame part and at right angles to the frame part of thesegmentation elements. The spacers of all the segmentation elements forman inner cylinder around the longitudinal axis of the housing cylinderand effect an

[0051] additional fixing of the segmentation elements. The spacers canhave openings in a preferred embodiment.

[0052] Just like their specific arrangement inside the module accordingto the invention, the specific configuration of the segmentationelements according to the invention has the effect that the total volumeof the free spaces between the hollow fibers is substantially enlargedagain, and is therefore much larger than in the case of the modulesdescribed in the prior art. That is to say, in such modules according tothe invention the packing density is substantially reduced again by theinstallation of the segmentation elements according to the invention. Inthe hollow fiber membrane modules according to the invention thatcontain segmentation elements, the packing density of the hollow fibermembranes, when referred to all the hollow fibers of a bundle of ahollow fiber membrane module according to the invention, is at most 20%,preferably at most 10%, while, referred to the total number of all thehollow fibers of all the bundles, the packing density is under 10%,preferably under 5%.

[0053] By contrast with the conventionally employed spacer material, theinstallation of the segmentation elements according to the invention inthe hollow fiber modules, in particular the relatively large passagesurface embraced by the frame part, ensures that a virtually unimpededexchange of liquid is ensured between the individual compartments of themodule, and thus between the individual hollow fiber bundles. Since theresistance of the module is substantially reduced on the basis of thispassage surface by comparison with the flow of the solution or themedium, the flow can flow more effectively through the module and thusmore effectively prevent the formation of deposits on the surfaces ofthe individual hollow fibers. Since the pressure loss of the flow issimultaneously minimized, there is, however, no need for additionalexpenditure of energy for the flow through the module, as is requiredwith modules known in the prior art in which conventional spacers areused.

[0054] In a further particularly preferred embodiment of the invention,it is provided that the segmentation elements are fastened on the outersurface of a first housing cylinder whose lateral surface preferably hasopenings. The hollow fiber membrane bundles are arranged in this case inthe interspaces, defined by the spaced apart segmentation elements, orcompartments on the outside of the lateral surface of the first housingcylinder, preferably additionally being fixed, for example by holdingrings. In a preferred embodiment, the entire module is located inside asecond cylindrical housing that is preferably designed as a cage whichforms the outer boundary of the packing space and serves chiefly forstabilizing the hollow fiber membrane module.

[0055] Of course, membrane modules according to the invention can alsohave segmentation elements inside and outside the first, that is to sayinner, housing.

[0056] In a particularly preferred embodiment of the present invention,it is provided that all the components of the hollow fiber membranemodule according to the invention, that is to say housings, hollowfibers and segmentation elements, consist of materials that can besterilized with superheated steam.

[0057] Depending on which membrane is inserted into the module, that isto say whether a microfiltration, ultrafiltration, nanofiltration ordialysis membrane is involved, the hollow fiber membrane moduleaccording to the invention is suitable, in particular, for use in thefiltration or dialysis of media that have a powerful fouling effect. Forexample, the hollow fiber membrane module according to the invention canbe used as what is termed reactor dialysis membrane module in fermentersfor removing metabolic products of the fermented cells and/or forfeeding nutrients. A further use can take place in bioreactors, in feedand bleed mode, in order to remove liquid with products from thereactor.

[0058] The invention also relates to methods for producing theabovenamed hollow fiber membrane modules, in particular modules thathave several hollow fiber membrane bundles because of the use ofsegmentation elements. In a preferred embodiment, a smooth material orshaped piece that is flat on the spatial projection and is intended toform a later lateral surface of the first or only, preferablycylindrical housing is provided in this case with segmentation elements.The segmentation elements can, for example, be fitted or clipped on aflat material of the lateral surface with the aid of elementsspecifically provided therefore, for example knobs. Consequently, thematerial of the lateral surface is held together or rolled up to form acylinder of circular or other shape, for example of rectangular crosssection. In this case, the material of the lateral surface can be rolledup such that the segmentation elements are located on the inner surfaceof the cylinder. Moreover, the material of the lateral surface can alsobe rolled up such that the segmentation elements are located on theouter surface of the cylinder. In one embodiment, before the housingcylinder is rolled up, the hollow fibers can be inserted into theinterspaces or compartments, provided by the fastened segmentationelements, in a desired arrangement and in accordance with the providedpacking density, it being possible to fix the hollow fibers beforerolling up, if appropriate. In this case, after being rolled up thehousing cylinder is subsequently closed and sealed in the usual way atthe cylinder ends. In another embodiment, the hollow fibers can,however, also be inserted into the compartments defined by thesegmentation sections after the housing cylinder is rolled up. Themodule can preferably be inserted into a second housing cylinder, whichis designed as a cage in a preferred form.

[0059] The invention also relates to methods that are simple andcost-effective to carry out for the purpose of producing hollow fibermembrane modules. The method is defined, inter alia, by virtue of thefact that a flat-shaped piece that is provided with openings andintended to form the later lateral surface of the cylindrical housing isbrought into a cylindrical shape by being rolled up, and hollow fibermembranes are arranged in and/or around the housing. Depending on whichproperties the material to be rolled up exhibits in the spatialprojection, for example whether it is flexible or relatively rigid,whether it is designed in one piece and, for example, does or does notinclude notches at which the material can be bent, or whether itcomprises several parts that are, for example, of identical dimensions,which are connected to one another via hinges or similar elements,preferably, the cross section of the cylinder thereby obtained can becircular or polygonal. The housing material can be designed as aflexible mat, a flexible lattice, a mat with a hinge-like part etc. Itis also possible thereafter for the hollow fibers provided to beintroduced into the housing cylinder thus obtained in the desiredarrangement and with the desired packing density.

[0060] In a further preferred embodiment of the present invention, it isprovided that further parts, in particular segmentation elements are,(already) fitted on the flat shaped piece used to form the housingcylinder, said elements, being suitable for separating individual hollowfiber bundles spatially from one another in the later housing cylinderand/or for lending the housing cylinder additional stability. Thesesegmentation elements can have been produced together, for example usingan injection-molding or casting process, for example in one operationwith the material used to form the housing cylinder. That is to say, thematerial that is to be rolled up to form the cylindrical shape and isprovided with segmentation elements can be designed in one piece. Thesegmentation elements can, however, also have been produced separately,and subsequently be fitted or clipped on or fastened in a similar way onor in the lateral surface of the housing at elements, for example knobs,provided for the purpose.

[0061] The material of the lateral surface is subsequently rolled up toform a cylinder. In this case, the material of the lateral surface canbe rolled up such that the segmentation elements are located on theinner surface of the cylinder to produce a hollow fiber membrane moduleaccording to the invention whose housing interior is subdivided intocompartments by the segmentation elements. However, the material of thelateral surface can also be rolled up such that the segmentationelements are located on the outer surface of the cylinder. In this case,however, there is also the possibility, in particular, firstly ofrolling the material cylinder together and then clipping thesegmentation elements outside onto the cylinder thus formed, orfastening them in a suitable way.

[0062] In one embodiment of the method according to the invention,before the housing cylinder is rolled up, the hollow fibers can beinserted in the desired order and in accordance with the prescribedpacking density into the interspaces or compartments prescribed by thefastened segmentation elements. Before the housing cylinder is rolledup, the hollow fibers are preferably fixed on the segmentation elements,use being made, in particular, of thin lattices, cable ties or similarelements. In this case, after being rolled up the housing cylinder issubsequently closed and sealed in the usual way at the cylinder ends bypotting the fiber ends in the usual way. In another embodiment, thehollow fibers can, however, also be inserted after the housing cylinderhas been rolled up into the compartments defined by the segmentationsections, and be fixed in a suitable way inside the compartments. Afterthe module thus obtained has been filled with the hollow fiber bundles,the housing cylinder is subsequently closed and sealed at the cylinderends in the usual way by potting the fiber ends in the usual way.Thereafter, the module fitted with the hollow fiber membrane bundles isinserted into a second housing cylinder that is preferably designed as acage, and is thereby stabilized.

[0063] With regard to the Figures, identical reference numerals refer todevices or elements thereof that are identical in design or/andfunction.

[0064]FIG. 1a) shows in schematic form the housing lateral surface orthe wall 1 of a hollow fiber membrane module 100 according to theinvention, which wall can be rolled up into the hexagonal shape of ahousing 3 represented by the example in cross section in FIG. 2a).Fitted on the wall 1 are rectangular segmentation elements 5 of lengthL_(S) and height H_(S) that are uniformly spaced apart. The length L_(S)of the segmentation elements corresponds to the length L_(M) of thehousing 3. The height H_(S) corresponds approximately to 90 to 95% ofhalf the height of the housing 3. Constructed in the housing lateralsurface 1 are lines of weakness 39 that are uniformly spaced apart andalternate with the segmentation elements 5, and which facilitate thefolding over of the housing lateral surface 1 into the final shape ofthe housing 3 and, in the final shape, form the edges of the housing 3of FIG. 2, which is of hexagonal cross section.

[0065] Various embodiments of segmentation elements 5 are shown in FIGS.1b), c) and d). The segmentation elements 5 respectively comprise arectangular frame part 7 that surrounds the passage surface 9. Thepassage surface 9 is subdivided into smaller individual surfaces by thestabilization elements 11, which are designed as connecting bars orlattices. Moreover, the segmentation elements 5 have at each of theirends two fastening elements 13 that resemble extensions and serve forfastening the segmentation elements 5 on the wall 1. The fasteningelements 13 have two limbs 35 and 37 which enclose a right angle. Thelimb 35 is seated on the longitudinal side of the segmentation element5, whereas the second limb 37 points away from the segmentation element5.

[0066]FIG. 1a) also shows in a schematic form the arrangement of hollowfibers 33 between two adjacent segmentation elements 5, and hollow fiberbundles 17 in compartments 21.

[0067]FIG. 2a) shows a perspective illustration of the shape of thehousing 3, which is hexagonal when seen in cross section. Starting fromthe illustration of the wall 1 in FIG. 1a), the wall 1 is rolled up toproduce the module 100 by virtue of the fact that the segmentationelements 5 project into the interior 18 of the cylinder 3 and subdividethe latter into the compartments 21. The height Hs of the segmentationelements 5 corresponds approximately to half the height of the housing 3of the module according to the invention, such that in the case of theillustrated shape, hexagonal when seen in cross section, with in eachcase two opposite sides 70 of equal length arranged parallel to oneanother, the segmentation elements 5 arranged centrally perpendicular tothe sides 70 almost touch one another in the center of the housing 3.The interior or packing space 18 of the housing 3, that is to say theinner volume of the housing 3, is therefore virtually completelycompartmentalized. Also illustrated are the fastening means 13 forfastening the segmentation elements 5 on the lateral surface of thehousing 3. The cross section of the module according to the invention asin FIG. 2a) is illustrated in FIG. 2c). It is clearly to be seen thatthe edges 41 of the longitudinal sides of the segmentation elements 5that are averted from the housing inner surface 22 almost abut oneanother at the center of the packing space 18 and therefore formcompartments 21 that are separated from one another, or virtually so.The dimensions of the segmentation elements can in this case be suchthat all the edges touch in the middle, or nearly do so, as a result ofwhich they can then, if necessary, be fixed lightly against one anotherby suitable elements in order to increase the stability of the entiremodule. The cross sections 2 b) and 2 c) show further differentembodiments of the module 100. The two embodiments differ from oneanother in that in cross section 2 b) use is made of segmentationelements 5 that have spacers 29 arranged on the edge 41, averted fromthe inner surface 22 of the housing 3, of the longitudinal side, avertedfrom the inner surface 22, of the segmentation elements 5. The spacers29 can be designed as a material reinforcement of the longitudinal sideedge 41 of the segmentation element 5. It can also be provided that thelongitudinal side edge 41, facing the center of the packing space 18, ofthe segmentation element 5 has a bent-over part, reinforcement,attenuation or similar on both sides at a right angle in each case. Thespacers 29 of the segmentation elements 5 in this case enclose a secondinterior 31 over the entire length of the housing 3. Seen in crosssection, the spacers 29 have a T-profile as an extension of thesegmentation element 5, the limbs 50, 51 of the T projecting at a rightangle from the segmentation element 5, abutting the limbs of an adjacentspacer 29 and thus forming a hexagonal interior 31 when seen in crosssection. The spacers 29 can have openings (not illustrated here).Illustrated in some compartments 21 are hollow fibers 33 lying looselyagainst one another. Also illustrated is the free space 43 in thepacking space 18.

[0068]FIG. 3a) shows a perspective illustration of a further embodimentof a hollow fiber membrane module 100 according to the invention. Theillustration shows a cylindrical housing 3 whose lateral surface 1 ispierced by numerous perforations or openings 25. The segmentationelements 5 are arranged on, for example fitted on the outwardly facingsurface of the housing 3. Also illustrated are the stabilizationelements 11, designed as transverse connecting bars, in the segmentationelements 5. Finally, FIG. 3a) shows the holding rings 27, which arearranged concentrically around the housing 3 and around the segmentationelements 5, pointing radially outward, with which they also makecontact, and serve for fixing hollow fiber membranes (not illustratedhere) that are to be inserted into the compartments 21. Also illustratedis the packing space 18, which is formed on the inside by the outersurface of the housing 3, and at the outside by an imaginary lateralsurface 47 which surrounds the segmentation elements 5, makes contactwith the outer edges 60 thereof and follows the course of the holdingrings 27. This imaginary lateral surface 47 is arranged concentricallyaround the inner housing 3 at a spacing of height Hs.

[0069]FIGS. 3b), 3 c) and 3 d) show various embodiments of segmentationelements 5 used in accordance with the invention, FIGS. 3b) and 3 c)differing in the number of transverse connecting bars 11 and the numberof the individual passage surfaces 45 formed thereby.

[0070] Stabilization elements 11 designed as a matrix or lattice areillustrated in FIG. 3d).

[0071]FIG. 4 shows a perspective view of a similar hollow fiber membranemodule to that in FIG. 3a). It is shown here that hollow fiber membranebundles 17 whose length is equal to the length of the module 100 arearranged in the individual compartments 21. Here, as well, the packingspace 18 is defined as the volume that is formed between the outersurface of the housing 3 and the inner surface of the imaginary lateralsurface 47, which surrounds the segmentation elements 5 and makescontact with the outside edges 60 thereof and the course of which isprescribed by the course of the holding rings 27. The enveloping lateralsurface 47 is the surface that results when the outwardly pointinglongitudinal edges 60 of the segmentation elements 5 are connected toone another around the circumference of the module 100, such that theenveloping lateral surface 47 is arranged concentrically around theinner housing 3.

[0072]FIG. 5 shows a further exemplary embodiment of the moduleaccording to the invention, which was fashioned from stainless steelwire. In this embodiment, one segmentation element and one part of thelateral surface each form permanently interconnected units that arefixed to one another with the aid of eyelets and can therefore be movedwith respect to one another such that, in accordance with the schematicFIG. 1, they can be developed situated one behind another into a plane.The surface of the segmentation element is inclined to the lateralsurface by an angle of approximately 45 degrees. FIG. 5.a shows adevelopment of the module housing, while FIG. 5.b shows the crosssection of the module when folded together, without the hollow fibersthat are to be inserted into the compartments.

[0073]FIG. 6 shows a variant of the exemplary embodiment illustrated inFIG. 2. In this variant, the segmentation elements are only as long asthe potting, and they are arranged in each case in the middle and atboth ends of the module.

What is claimed is:
 1. A hollow fiber membrane module for filtration,diafiltration dialysis methods, comprising at least one housing and aplurality of tubular hollow fiber membranes which are arranged parallelto one another in and/or around the housing in a packing space, whereinthe volumetric ratio of all the hollow fiber membranes arranged in thepacking space to the packing space is less than 20%.
 2. The hollow fibermembrane module as claimed in claim 1, in which the housing has acylindrical shape.
 3. The hollow fiber membrane module as claimed inclaim 1, in which the lateral surface of the housing is provided withopenings.
 4. The hollow fiber membrane module as claimed in claim 3, inwhich the openings projected onto a plane are shapes selected fromsquares, rectangles and circles.
 5. The hollow fiber membrane module asclaimed in claim 3, in which the openings have dimensions of 3 to 20 mm.6. The hollow fiber membrane module as claimed in claim 3, in which theratio of the total surface area of the openings to the total surfacearea of the housing lateral surface is approximately 0.2 toapproximately 0.9.
 7. The hollow fiber membrane module as claimed inclaim 1, in which the hollow fiber membranes consist of a ceramic and/orpolymeric material or comprise the same in substantial proportions. 8.The hollow fiber membrane module as claimed in claim 7, in which thehollow fiber membranes including the support structure have a thicknessof approximately 5 μm to approximately 300 μm.
 9. The hollow fibermembrane module as claimed in claim 7, in which each of the hollow fibermembranes has an inside diameter of up to 2 mm.
 10. The hollow fibermembrane module as claimed in claim 1, in which the hollow fibermembranes are arranged in the module in the form of at least one bundle.11. The hollow fiber membrane module as claimed in claim 10, in whichthe hollow fibers are rolled up as bundles in the form of mats with awide fiber spacing, and the fibers being brought to a spacing adapted tothe packing density in the region of the pottings by the wrapping ofconventional spacer materials.
 12. The hollow fiber membrane module asclaimed in claim 10, in which at least two hollow fiber membrane bundlesare separated from one another by at least one segmentation elementfitted on the lateral surface of the housing.
 13. The hollow fibermembrane module as claimed in claim 12, in which the at least onesegmentation element comprises a frame part with a free passage surfacesurrounded by the frame part.
 14. The hollow fiber membrane module asclaimed in claim 13, in which the free passage surface of the frame partis subdivided by stabilization elements.
 15. The hollow fiber membranemodule as claimed in claim 14, in which the total surface area of thestabilization elements referred to the free passage surface surroundedby the frame part is approximately 2% to approximately 20%.
 16. Thehollow fiber membrane module as claimed in claim 13, in which the atleast one segmentation element is fitted on the inner surface of thehousing and the interior of said housing is subdivided intocompartments.
 17. The hollow fiber membrane module as claimed in claim12, in which the at least one segmentation element is fitted on theouter surface of the housing and subdivides the space located over theouter surface of the lateral surface into compartments.
 18. The hollowfiber membrane module as claimed in claim 17, in which the housing withthe at least one segmentation element fitted on the outer surface of thelateral surface is accommodated in a second cage-like housing.
 19. Thehollow fiber membrane module as claimed in claim 12, in which the lengthof at least one segmentation element corresponds to the length of thehousing.
 20. The hollow fiber membrane module as claimed in claim 12, inwhich the segmentation elements are shorter than the housing and aredistributed over the length of the housing with appropriate axialinterspaces, no further segmentation element being arranged inside theseaxial interspaces over the full azimuth angle inside the housing. 21.The hollow fiber membrane module as claimed in claim 12, in which thesegmentation elements are as long as the pottings provided at the endsand are arranged at the end of the housing such that the pottings aresegmented.
 22. The hollow fiber membrane module as claimed in claim 16,in which hollow fiber membranes are arranged in at least one compartmentproduced by at least two segmentation elements.
 23. The hollow fibermembrane module as claimed in claim 22, in which the hollow fibermembranes arranged in at least one compartment are fixed on at least onesegmentation element.
 24. The hollow fiber membrane module as claimed inclaim 23, in which the packing density of all the hollow fiber membranesis smaller than 20%.
 25. The hollow fiber membrane module as claimed inclaim 1, which further comprises a housing connection for feeding aliquid into the fiber interior of the hollow fiber membranes and ahousing connection for withdrawing a liquid from the fiber interior. 26.The hollow fiber membrane module as claimed in claim 1, in which all theconstituents are produced from a material capable of being sterilizedwith water vapor at 121° C.
 27. A method for producing a hollow fibermembrane module, comprising rolling a shaped piece together to produce ahousing shape, and arranging the hollow fiber membranes in and/or aroundthe housing in a packing density of less than 20%.
 28. The method asclaimed in claim 27, wherein the shaped piece is provided with openings.29. The method as claimed in claim 27, wherein the shaped piece isrolled to produce a cylindrical housing.
 30. The method as claimed inclaim 27, wherein the shaped piece comprises segmentation elements. 31.The method as claimed in claim 27, in which before or after rolling theshaped piece together, segmentation elements are fitted at spacings onthe shaped piece.
 32. The method as claimed in claim 30, wherein theshaped piece is rolled together such that the segmentation elements arelocated on the inner surface of the rolled shaped piece.
 33. The methodas claimed in claim 31, wherein the shaped piece is rolled together suchthat the segmentation elements are located on the outer surface of therolled shaped piece.
 34. The method as claimed in claim 27, in whichbefore the shaped piece is rolled together, at least one hollow fibermembrane bundle is arranged and fixed on the shaped piece.
 35. Themethod as claimed in claim 30, in which before the shaped piece isrolled together, at least one hollow fiber membrane bundle is arrangedand fixed on the shaped piece in the compartment between two adjacentsegmentation elements.
 36. The method as claimed in claim 31, in whichbefore the shaped piece is rolled together, at least one hollow fibermembrane bundle is arranged and fixed on the shaped piece in thecompartment between two adjacent segmentation elements.
 37. The methodas claimed in claim 27, in which after the shaped piece has been rolledtogether, at least one hollow fiber membrane bundle is arranged andfixed in the housing.
 38. The method as claimed in claim 30, in whichbefore the shaped piece is rolled together, at least one hollow fibermembrane bundle is arranged and fixed in the housing in the compartmentbetween two adjacent segmentation elements.
 39. The method as claimed inclaim 31, in which before the shaped piece is rolled together, at leastone hollow fiber membrane bundle is arranged and fixed in the housing inthe compartment between two adjacent segmentation elements.
 40. Themethod as claimed in claim 27, in which the ends of the hollow fibermembranes are potted, and further comprising sealing the housing at itsends.
 41. The method as claimed in one of claim 27, in which the housingis inserted into a second housing.
 42. The hollow fiber membrane moduleas claimed in claim 9, wherein the hollow fiber membranes have an insidediameter of from about 0.15 mm to about 0.8 mm.
 43. The hollow fibermembrane module as claimed in claim 11, wherein the bundles compriseless than 10 fibers per centimeter.
 44. The hollow fiber membrane moduleas claimed in claim 17, in which hollow fiber membranes are arranged inat least one compartment produced by at least two segmentation elements.45. The hollow fiber membrane module as claimed in claim 37, in whichthe hollow fiber membranes arranged in at least one compartment arefixed on at least one segmentation element.
 46. The hollow fibermembrane module as claimed in claim 38, in which the packing density ofall the hollow fiber membranes is smaller than 20%.
 47. The hollow fibermembrane module as claimed in claim 1, wherein the tubular hollow-fibermembranes have the same or different diameters.